30 research outputs found
Micro-flow visualization of magnetic nanoparticles for biomedical applications
An investigation to measure the flow behavior of magnetic nanoparticles through a 100mm
microchannel is conducted. The magnetic field is applied externally by a permanent magnet and by using a
micro-PTV system it was possible to measure the flow behavior of magnetic nanoparticles at different
flow rates and magnetic fields through a 100mm glass capillary. A strong dependence on both magnetic
and hydrodynamic force is observed on the nanoparticles fluidic paths. Based on these in vitro studies,
important parameters and issues that require further understanding and investigation are point out
Influence of Hydrogen Annealing on the photocatalytic activity of diamond supported gold catalysts
Fenton-treated diamond nanoparticles have been
submitted to hydrogen reduction at 500 °C with the purpose of
modifying the nature of the functional groups present on the
diamond surface. The nature of the functional groups on the
diamond samples was characterized by a combination of
spectroscopic and analytical techniques. In particular, Fouriertransformed
infrared spectroscopy, temperature-programmed
desorption, and X-ray photoelectron spectroscopy (XPS) show
the decrease in the population of carboxylic acids, esters, and
anhydrides after hydrogen treatment. XPS also shows a decrease
on the oxygen content after the hydrogen treatment of the
diamond nanoparticles and lower electronegativity of the carbons
as assessed by the lower binding energy values. Although Fentontreated
diamond colloids in water changes the zeta potential from positive to negative values as a function of the pH, hydrogen
annealing and the disappearance of the carboxyl groups determines that the zeta potential of the resulting sample remains
positive in the complete pH range. Deposition of gold nanoparticles was carried out by the polyol method consisting on the
reduction of HAuCl4 by hot ethylene glycol in the presence of the support. TEM analysis shows a variation of the average gold
nanoparticle size that decreases after hydrogen reduction of carboxylic groups and becomes smaller for low gold loadings. The
catalytic activity of the diamond supported gold nanoparticles as a function of the surface annealing treatment and gold loading
was evaluated for the natural sunlight-assisted peroxidation of phenol by H2O2. It was observed that the most efficient sample was
the one having lower gold nanoparticle size that was obtained for diamond samples reduced by hydrogen at 500 °C after the
Fenton treatment and having low gold loading (0.05 wt %). Turnover frequencies above 2400 and 940 h−1 were obtained for
phenol degradation and H2O2 decomposition, respectively.Financial support by the Spanish Ministry of Economy and Competitiveness (MINECO, Severo Ochoa program and CTQ 2012-32315), Universidad Politecnica de Valencia (PAID-06-11, no 2095) and Generalitat Valenciana (Prometeo 2013/014 and GV/2013/040).Navalón Oltra, S.; Sempere Aracil, D.; Alvaro Rodríguez, MM.; García Gómez, H. (2013). Influence of Hydrogen Annealing on the photocatalytic activity of diamond supported gold catalysts. ACS Applied Materials and Interfaces. 5(15):7160-7169. https://doi.org/10.1021/am401489nS7160716951